1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus such as, for example, circuit breakers. The invention also relates to tools for manipulating electrical switching apparatus.
2. Background Information
Electrical switching apparatus used in power distribution systems are often mounted within a housing structure (e.g., without limitation, switchgear enclosure) either individually or in combination with other switchgear (e.g., without limitation, circuit switching devices and circuit interrupters such as circuit breakers, contactors, motor starters, motor controllers and other load controllers).
Some electrical switching apparatus such as, for example, some medium voltage and low voltage circuit breakers, can be relatively large. In order to facilitate movement (e.g., installation; removal; replacement; maintenance), a sizeable circuit breaker is commonly coupled to rollers, which permit such circuit breaker to be drawn out of the housing assembly. Accordingly, such circuit breakers are commonly known in the art as “draw-out” circuit breakers. The process of moving the circuit breaker into the housing is commonly referred to as “racking” the circuit breaker.
The enclosure, which houses the draw-out circuit breaker, generally includes side walls, a top, a bottom, a door and a draw-out mechanism. The draw-out mechanism includes, for example, a combination of rails and rollers on one or both of the side walls of the enclosure and the sides of the circuit breaker. The circuit breaker may be further supported within a draw-out frame, commonly known in the art as a cassette or chassis. Draw-out circuit breakers are described in further detail, for example, in commonly assigned U.S. Pat. No. 7,019,229, which is hereby incorporated herein by reference.
To facilitate movement (e.g., drawing out; racking) of the circuit breaker with respect to the housing structure, some draw-out circuit breakers further include a suitable mechanism such as, for example and without limitation, a number of racking screws and/or a linkage assembly that interconnects the circuit breaker and the housing structure. Typically, the mechanism further includes an interface disposed on the circuit breaker. The interface is actuatable mechanically, for example, by a mechanical tool (e.g., without limitation, hand crank), or electronically, for example, by a motor-driven device, to draw out or rack in the circuit breaker, as desired.
U.S. Pat. No. 5,278,722, for example, discloses a switchgear racking mechanism including a self-retaining crank and draw-out unit position indicator.
U.S. Pat. No. 5,477,017, for example, discloses an electric racking device for racking circuit breakers into switchgear.
U.S. Pat. No. 7,019,230, which is hereby incorporated herein by reference, discloses a racking device and power module therefor.
Among the disadvantages of the foregoing mechanisms are that they are either relatively complex and bulky, for example, in the case of known electric racking devices, or in the case of mechanical devices (e.g., tools), the tools are not designed so as to optimize their utility (e.g., without limitation, mechanical leverage). Misplacement or loss of the tool is also a concern, because it is generally a separate component from the circuit breaker.
There is, therefore, room for improvement in electrical switching apparatus such as, for example, draw-out circuit breakers.
There is also room for improvement in tools for facilitating movement of electrical switching apparatus.